Rock drill



Dec. 14, '1943. L. A, B HUTTON 2,336,935

ROCK DRILL Filed sept. 22, 1943" ,Patented Dec. 14, 1943 UNITED i STATES j PATENT VoFFlcE ROCK DRILL Lionel Alfred Bennett Hutton, Ottawa, Ontario,

Canad Application September 22, 1943, Serial No. 503,334

Ill Canada, April 3, 1943 l 6 Claims.

This invention relates to rock drills ofA the detachable bit type, the present application being a division of copending application, Serial No. 482,365, filed April 9, 1943. I

The use of detachable bits for rock drills has now become quite widespread in the mining industry due to many obvious advantages thereof. It is well recognized, however, that there is room for improvement in many of means heretofore proposed for attaching or locking the bit to the shank of the drill. The common dovetail has been frequently employed as such locking means. One of the disadvantages of the dovetail is that unless tolerances are very accurate and close, play develops between the bit and shank and an appreciable loss of energy occurs. If, however,

operating position therbit is easily removed from the shank by slight counter rotation.

Other objects and advantages of the invention -1 drill including the bit of Figure 3.

tolerances are very close, it is diilicult to insert -and remove the bit from the shank. If tolerances are such as to permit ease of insertion or withdrawal of the bit from .the shank, there is a tendency of the bit to slide sidewise when the drill is operating in broken or soft rock or when it enters a iissure.

The object of the present invention is to provide a rock drill construction in which the detachable bit may be readily attached and removed from the shank; in which the bit is positively held in position during the normal rotating operation of the drill in which despite wear in use, there is maintained throughout the useful life of the bit a substantial area of intimate surface contact between the blt and shank to reduce greatly loss of energy in operation and to prolong the life of the Referring, to Figures 1 and 2, the bit l has a transversely extending curved tongue 2 in the shape of a dovetail on the upper end thereof.

Theton ue has arcuate parallel sides, as shown,

and extends from one edge of the bit to aA point adjacent but spaced from the opposite edge. The shank 3 has a complementary curved recess 6 in 'its lower end to receive the tongue. It ,will be observed that such a recess is open at one endfor entrance of the tongue thereinto and closed at the other end to provide a stop i8 for the tongue. The recess is preferably somewhat deeper than the'tongue to provide a clearance, as

4indicated at 5, between the top of the tongue and shank by reducing wear due to play between the I shank and bit; and in'which the means for locking the bit in position on the shank at the same time insures the intimacy of contact between the complementary bearing surfaces of the bit and shank. l The invention contemplates the provision, on the end of one of the members of a rock drill, of

a tongue having side walls the longitudinal contours of which are in the form of concentric arcs, the tongue also having a somewhat enlarged head portion extending at right angles to the axis of the member, and the other member having a complementary recess to receive the tongue.

These complementary curved surfaces insure, during normal rotating operation of the drill, that th bit and shank remain locked in intimate contact over their complementary bearing surfaces.

This avoids loss of impact energy usedin operating the drill, and, at the same time, prevents unintentional displacement or loss of the bit in a drill hole. Despitethis intimate contact in the the bottom of the recess. Thus, the major portions 6 and 'i of the end surfaces of the bit and shank, respectively, have positive and intimate contact with each other to eliminate substantial loss of energy during operation `of the drill.

Referring to Figures 3 and 4, the bit 8 has a curved dovetail-shaped recess 9 transversely extending from edge to edge thereof. The recess is quite broad whereby the bottom surface i0 there-l of constitutes the major bearing portion of the end surface of the bit. The sides of the recess are in the form of arcs the geometrical center of each of which lies on a line passing through the center of the bit.l A stop il is provided at one end of the recess.l The shank l2 has a complementary tongue I3 on the end thereof and a recess It to receive the stop Il. In this instance clearance, as indicated at i5, is preferably Aprovided on the opposing portions I6, I6' of the bit and Il, Il of the shank -to ensure positive bearing contact of' the major bit surface I0 with the complementary surface of the shank.

' The usual water hole 50 may be provided.

The substantial. area of bearing. contact between bit and shank is suiilcient forA transmission of thev impact f rce of the drill without injury to either member ue to the intimate and uniform contact which is provided throughout such area.

I claim: 1. In a rock drill bers, a 'tongue on the end o! one of the members,

v -at least one end of the tongue coinciding with the edge. of said end oi the member, said tongue having side walls the longitudinal contours oi' which are in the lform of concentric arcs andan enlarged head extending atV rightangles to l longitudinal .,axis oi the member, the other mem- -ber having a complementary recess to receive the tongue 'and means ior limiting movement of the tongue in the recess comprising a stop on one of the members.

2. In a rock drill bit, means thereon for attaching it to a shank comprising a tongue on one end thereoLsaid tongue having side walls the longitudinal contours .oi whichare in the form of concentric arcs and an enlarged head extending at right angles to the longitudinal axis the bit to apoint adjacent but spaced from 'othe bit, said tongue extending from one edge 0 the opposite edge ot the bit.

having Aim and shank mem-` cur-ing. said members togetherv comprisingl a curved tongue on the end of one member, said tongue having an enlarged head extending at angles to the longitudinal axis oi the -memright ber, said tongue extending from one edge of the member to a point l'adjacent but spaced from the opposite edge. of the member, the other member having a complementary recess receiving said tongue.

5. In a rock drill having bit and shank mem-v end relation', means setogether comprising a bers mounted in end to curing said members .curved'tongue on. the end of onemember, said ton e having aneniarged head extending from edg to edge oi the member at right angles to the longitudinal axis thereof, the sides of the tongue being' in the Iorm of arcs the geometrical centers oi which lie on a line passing through the center of the member, .the other member having a complementary recess receiving said tongue, a stop carried byv one oi the members, and a recess in the other member for engagement by thestop.

6. A rock dril1 bitcomprising a body member, a curved dovetail tongue on the end oi the member, the top surface of the tongue lying in a plane at right angles to the longitudinal 'axis oi! the member, said. tongue 'having parallel 'arcuate sides and extending from one edge of the member to a point adjacent` but spaced from the oppo 'site edgeof the member.

LIONEL ALFRED BENNET'I'" HU'ITON. 

